Figure 10. Effect of CPZ on oxonol VI fluorescence under Na⁺,K⁺ exchange conditions.

Liposomes containing 30₂ were used and the experiment was performed as in A. Extravesicular K⁺ was diluted more than 70 folds following addition of liposomes to the medium. The ATP concentration used to start the reaction was 75 µM. The numbers indicate the percentage decrease in maximum fluorescence occurred by pretreatment with 25 µM ADP. P₁ and P₂ denote the rapid and the slow phases of fluorescence response occurring in the presence of extracellular (intravesicular) K⁺.